Axial Fan For A Cooling Fan Module

ABSTRACT

An axial fan for a cooling fan module, includes a hub having a front wall configured to be connected to a rotor of an electric motor at a plurality of connection points, and a side wall from which a plurality of blades extend. At least one opening is formed in the front wall of the hub and between at least one of the connection points and the side wall. The at least one opening comprises a curved portion extending in a circumferential direction with respect to an axis of the hub.

CROSS REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application is a continuation-in-part of co-pending application Ser. No. 14/694,668 filed on 23 Apr. 2015, for which priority is claimed under 35 U.S.C. § 120, and this application claims priority of Application No. TO2014A000340, filed in Italy on Apr. 23, 2014 under 35 U.S.C. § 119, the entire contents of which are fully incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an electric fan for a cooling fan module, in particular for a heat exchanger, such as a radiator, of a motor vehicle.

BACKGROUND OF THE INVENTION

More specifically, the present invention relates to an axial fan for use in such a module, comprising an essentially cup-shaped central hub with a front wall intended to be connected to the rotor of an electric motor at a plurality of connection points or areas, and a side wall from which a plurality of outer blades extend.

These fans are generally fixed to the rotor of the drive motor by means of screws or bolts.

During operation the motor generates considerable vibrations which are transmitted to the fan and cause the generation of an acoustic noise which is somewhat bothersome for the human ear, in particular at the low and middle range speeds.

SUMMARY OF THE INVENTION

Hence there is a desire for a fan of this type designed so as to overcome the abovementioned drawback of fans according to the prior art.

According to one aspect, the present invention provides an axial fan for a cooling fan module, including a hub having a front wall configured to be connected to a rotor of an electric motor at a plurality of connection points, and a side wall from which a plurality of blades extend. At least one opening is formed in the front wall of the hub and between at least one of the connection points and the side wall. The at least one opening comprises a curved portion extending in a circumferential direction with respect to an axis of the hub.

Preferably, a plurality of openings are provided in the front wall of the hub, each opening comprises the curved portion which is circular arc shaped and arranged between a corresponding connection point and the side wall.

Preferably, the curved portions and the hub are concentric.

Preferably, each curved portion comprises a radial inner edge and a radial outer edge, and the radial inner edge is circular arc shaped.

Preferably, the radial outer edge is circular arc shaped.

Preferably, the radial inner edge and the radial outer edge of each curved portion are concentric.

Preferably, the radial inner edges of the curved portion are on a same circle centered on the axis of the hub, the radial outer edges of the curved portion are on a same circle centered on the axis of the hub.

Preferably, the radial width of the curved portion ranges from 1 mm to 6 mm.

Preferably, the radial width of the curved portion ranges from 1.5 mm to 4 mm.

Preferably, each curved portion has a center angle ranging from 15 degrees to 210/n degrees, and wherein n is the number of the openings.

Preferably, n is an integer greater than or equal to 3.

Preferably, the front wall of the hub has a plurality of through-holes respectively at the connection points, the through-hole is configured for receiving a fixing member to fix the hub to the rotor of the electric motor.

Preferably, an arc length of the curved portion exceeds a diameter of the corresponding through-hole.

According to another aspect, the present invention provides an axial fan for a cooling fan module, including a hub having a front wall configured to be connected to a rotor of an electric motor at a plurality of connection points, and a side wall from which a plurality of blades extend. At least one opening is formed in the front wall of the hub, the at least one opening comprises a curved portion formed between at least one of the connection points and the side wall.

Preferably, the front wall of the hub has a plurality of through-holes respectively at the connection points, the through-hole is configured for receiving a fixing member to fix the hub to the rotor of the electric motor, and the curved portion is intersected with a line passing through a center of a corresponding through-hole and an axis of the hub.

Preferably, the curved portion has a circular arc shape which protrudes radially outward.

Preferably, an arc length of the curved portion exceeds a diameter of the corresponding through-hole.

Preferably, a plurality of openings are provided in the front wall of the hub and equally spaced in a circumferential direction of the hub, and each opening comprises the curved portion.

Preferably, the radial width of the curved portion ranges from 1 mm to 6 mm.

Preferably, each curved portion has a center angle ranging from 15 degrees to 210/n degrees, and wherein n is the number of the openings.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of example only, with reference to figures of the accompanying drawings. In the figures, identical structures, elements or parts that appear in more than one figure are generally labeled with a same reference numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are generally chosen for convenience and clarity of presentation and are not necessarily shown to scale. The figures are listed below.

FIG. 1 is a front view of a fan according to the preferred embodiment of the present invention;

FIG. 2 is a partial view, on a larger scale, showing a detail of FIG. 1;

FIG. 3 is a partial perspective view, which shows fixing of a fan to the rotor of an electric motor; and

FIG. 4 is a partial front view of a fan of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the drawings 1 denotes overall an axial fan according to the preferred embodiment of the present invention. In the example embodiment shown the fan 1 comprises a substantially cup-shaped central hub 2. The hub 2 has a front wall 2 a intended to be connected to the rotor R of an electric motor M (FIG. 3) at a plurality of connection points 3. It should be realized that the term connection point may not be necessarily a single point and may include a connection area, in accordance with the type of fixing member or fastener used.

In the embodiment shown each connection point 3 comprises an essentially circular through-hole 4 for receiving a corresponding screw 5 for fixing the hub 2 to the rotor R (see FIG. 3).

As shown in FIG. 1, the front wall 2 a of the hub 2 of the fan has three connection points 3 in positions offset with respect to the axis X of the hub 2 and the fan and angularly equidistant.

The hub 2 also has an approximately cylindrical side wall 2 b substantially perpendicular to the front wall 2 a. A plurality of curved outer blades 6 extend from the side wall 2 b. Preferably, as shown, the outer ends of the blades 6 are connected to a peripheral ring 7 coaxial with the hub 2.

An opening is formed in the front wall 2 a of the hub 2, between the connection point 3 and the side wall 2 b. The opening includes a curved portion 10. The curved portion 10 is intersected with a line L passing through a center of the corresponding through-hole 4 and the axis X of the hub 2. The curved portion 10 preferably has a circular arc shape which protrudes radially outward. In the embodiment, a plurality of curved portions 10 are formed in the front wall, and equally spaced in a circumferential direction of the hub 2. Each curved portion 10 extends in the circumferential direction, relative to the axis X of the hub 2. The arc length of the curved portion 10 exceeds the diameter of the corresponding through-hole 4.

In the embodiment shown the curved portion 10 is in the form of circular arc or part of circle centered on the axis X of the hub. The curved portion 10 has a radial inner edge 10 a and a radial outer edge 10 b. The radial inner edge 10 a and the radial outer edge 10 b are circular arc shaped. In the embodiment, the opening further includes a plurality of straight portions 11 extending outward from the curved portion 10 along a radial direction of the hub 2. The radial outer edge 10 b of the curved portion 10 is discontinuous due to the presence of the straight portions 11. However, it should be noted that the straight portions 11 are not necessary. In the alternative embodiment, the front wall 2 a may not have the straight portion 11, consequently, the radial outer edge 10 b also may be a continuous circular arc.

In the embodiment, the radial inner edges 10 a and the radial outer edges 10 b are concentric, so the curved portion 10 has a uniform radial width in the circumferential direction. Preferably, the radial inner edges 10 a of the curved portions 10 are on the same circle centered on the axis X of the hub 2. The radial outer edges 10 b of the curved portions 10 are on the same circle centered on the axis X of the hub 2.

The arrangement is such that, during operation, the vibrations transmitted from the rotor R of the motor M to the front wall 2 a of the hub at the connection points 3 are propagated in the front wall 2 a towards the side wall 2 b following a path which has to go around the openings and which is therefore considerably longer than an essentially radial path which would instead exist in the absence of these openings. As a result, the vibrations are significantly dampened in the front wall 2 a of the fan hub, before they reach the side wall 2 b of this hub and then the blades 6 and the peripheral ring 7. The acoustic noise level generated during operation of the fan as a result of the vibrations transmitted from the electric motor is thus drastically reduced.

Conveniently, although not necessarily, the arc length of the curved portion 10 is at least equal to about 3 times, and preferably about 5 times, the diameter of the corresponding through-hole 4.

Referring to FIG. 4, each curved portion 10 has a center angle θ ranging from 15 degrees to 210/n degrees, wherein n represents the number of the openings, and is an integer greater than or equal to 3. The radial width Rw of the curved portion 10 ranges from 1 mm to 6 mm, preferably ranges from 1.5 mm to 4 mm. As labeled in FIG. 4, the radial width Rw is the radial width of the curved portion 10, and does not include the radial width of the straight portion 11.

The fan 1 may be conveniently made of molded plastic and the openings in the front wall 2 a of its hub 2 are conveniently formed during the fan molding operation.

In the description and claims of the present application, each of the verbs “comprise”, “include”, “contain” and “have”, and variations thereof, are used in an inclusive sense, to specify the presence of the stated item or feature but do not preclude the presence of additional items or features.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of example only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined by the appended claims. 

1. An axial fan for a cooling fan module, comprising: a hub, comprising a front wall configured to be connected to a rotor of an electric motor at a plurality of connection points, and a side wall from which a plurality of blades extend, wherein at least one opening is formed in the front wall of the hub and between at least one of the connection points and the side wall, the at least one opening comprises a curved portion extending in a circumferential direction with respect to an axis of the hub.
 2. The axial fan of claim 1, wherein a plurality of openings are provided in the front wall of the hub, each opening comprises the curved portion which is circular arc shaped and arranged between a corresponding connection point and the side wall.
 3. The axial fan of claim 2, wherein the curved portions and the hub are concentric.
 4. The axial fan of claim 2, wherein each curved portion comprises a radial inner edge and a radial outer edge, and the radial inner edge is circular arc shaped.
 5. The axial fan of claim 4, wherein the radial outer edge is circular arc shaped.
 6. The axial fan of claim 5, wherein the radial inner edge and the radial outer edge of each curved portion are concentric.
 7. The axial fan of claim 5, wherein the radial inner edges of the curved portion are on a same circle centered on the axis of the hub, the radial outer edges of the curved portion are on a same circle centered on the axis of the hub.
 8. The axial fan of claim 2, wherein the radial width of the curved portion ranges from 1 mm to 6 mm.
 9. The axial fan of claim 2, wherein the radial width of the curved portion ranges from 1.5 mm to 4 mm.
 10. The axial fan of claim 2, wherein each curved portion has a center angle ranging from 15 degrees to 210/n degrees, and wherein n is the number of the openings.
 11. The axial fan of claim 10, wherein n is an integer greater than or equal to
 3. 12. The axial fan of claim 2, wherein the front wall of the hub has a plurality of through-holes respectively at the connection points, the through-hole is configured for receiving a fixing member to fix the hub to the rotor of the electric motor.
 13. The axial fan of claim 12, wherein an arc length of the curved portion exceeds a diameter of the corresponding through-hole.
 14. An axial fan for a cooling fan module, comprising: a hub, comprising a front wall configured to be connected to a rotor of an electric motor at a plurality of connection points, and a side wall from which a plurality of blades extend, wherein at least one opening is formed in the front wall of the hub, the at least one opening comprises a curved portion formed between at least one of the connection points and the side wall.
 15. The axial fan of claim 14, wherein the front wall of the hub has a plurality of through-holes respectively at the connection points, the through-hole is configured for receiving a fixing member to fix the hub to the rotor of the electric motor, and the curved portion is intersected with a line passing through a center of a corresponding through-hole and an axis of the hub.
 16. The axial fan of claim 15, wherein the curved portion has a circular arc shape which protrudes radially outward.
 17. The axial fan of claim 16, wherein an arc length of the curved portion exceeds a diameter of the corresponding through-hole.
 18. The axial fan of claim 16, wherein a plurality of openings are provided in the front wall of the hub and equally spaced in a circumferential direction of the hub, and each opening comprises the curved portion.
 19. The axial fan of claim 15, wherein the radial width of the curved portion ranges from 1 mm to 6 mm.
 20. The axial fan of claim 15, wherein each curved portion has a center angle ranging from 15 degrees to 210/n degrees, and wherein n is the number of the openings. 